The roller type turntable is widely used in the indexing application of the machine tool, such as the indexing plate of the fourth axis or the cutter head of the tool magazine; in general, based on the position of the roller follower, the indexing driving mode of the roller type turntable can be divided into the driving mode of the roller gear cam and the driving mode of the barrel cam, so as to position the turntable in a preset position. Please refer to FIG. 1, which shows the driving mode of the roller gear cam, wherein the roller follower 10 is provided on the outer circumference of the turntable 11, and the central axis of each roller follower 10 is vertically radiated. The roller gear cam 12 drives the roller follower 10 on the outer circumference of the turntable 11, thereby drives the turntable 11 to rotate and be positioned at a preset position. Please refer to FIG. 2, which is so-called the driving mode of the barrel cam, the roller follower 20 is provided on the disk surface of the turntable 21, and the central axis of each of the roller follower 20 is parallel to the central axis of the turntable 21. The barrel cam 22 drives the roller follower 20 on the disk surface of the turntable 21, thereby drives the turntable 21 to rotate and be positioned at a preset position.
However, whether the roller gear cam or the barrel cam drives the driven roller of the turntable, the roller follower can only contact the rib wall on one side of the cam groove and make a rolling contact. There must be a gap between the cam groove of the roller gear cam or the barrel cam and the roller followers. When the turntable is driven, a so-called backlash is formed between the roller follower and the rib wall on the other side of the cam groove. Generally, the backlash is about 0.1 mm. Please refer to FIG. 2, as for the barrel cam, the roller follower 20 on the disk surface of the turntable 21 must contact on at least one side of the cam groove 221 of the barrel cam 22, and the roller follower 20 must also be rotatable in the cam groove 221.
Therefore, the groove width of the cam groove 221 of the barrel cam 22 must be slightly larger than the outer diameter of the roller follower 20 for the rotation of the roller follower 20, and the cam groove 221 is manufactured with the equal groove width. Therefore, when the roller follower 20 is guided in the cam groove 221, a gap is formed between one of the rib walls 222, 223 and the roller follower 20. Please refer to FIG. 3, when the barrel cam 22 rotates counterclockwise (CCW), the right rib wall 223 will contact and compress the roller follower 20 to drive the turntable 21 to rotate clockwise (CW), and a backlash with 0.1 mm width is formed between the roller follower 20 and the left rib wall 222 of the barrel cam 22. In contrast, please refer to FIG. 4, when the barrel cam 22 rotates clockwise (CW), the left rib wall 222 of the barrel cam 22 will contact and compress to the roller follower 20 to rotate the turntable 21 counterclockwise (CCW). A backlash with 0.1 mm width is formed between the roller follower 20 and the right rib wall 223. The existence of the backlash mentioned above not only causes the shock and the vibration between one of the rib walls and the roller follower when the barrel cam is started forward or backward, but also affects the positioning accuracy of the indexing rotation of the turntable and the machining accuracy of the workpiece. Therefore, the manufacturer is working to eliminate the backlash, but the existing problem of backlash cannot be effectively solved.
In view of this, the inventor has been engaged in research and development and production of related industries for many years, and has conducted in-depth research on the problems currently faced. After long-term efforts and research, the inventor has finally developed an effective elimination the problem of backlash between the cam component and the roller followers. The shortcomings of the prior art are improved effectively, which is the design tenet of the present invention.